POLICE yesterday airlifted bottles of water to thousands of parched drivers trapped on the M25 in scorching heat.

Sweltering motorists were stuck in an 18-mile traffic jam for up to five hours after a lorry burst into flames. Both carriageways were closed as temperatures hit 26C.

The nightmare scene came as experts predicted temperatures would soar to 81F today and water bosses applied for a drought order that could hit five million Londoners, including the Queen.

Surrey Police helicopter ferried the water to drivers after the truck fire near Leatherhead.

Paramedics treated three people at the roadside who suffered heat exhaustion. Anna Clark, of Maidstone, Kent, was trapped in the jam with her children Louise, six, and Ben, four. The 37-year-old said: "It was a nightmare.

"It was so hot just sitting there not able to do anything about it."

The lorry driver suffered minor burns.

Weather experts last night issued smog and heatwave alerts and predicted temperatures this weekend would be the highest this year.

And they warned England fans planning barbecues after the clash with Paraguay to drink plenty of water and protect themselves against the sun's intense rays. A Met Office spokesman said: "Most of the country will see these very high temperatures.

"I expect there will be lots of barbecues as people enjoy England's first World Cup match. But they must be careful."

Environment chiefs warned high ozone layers caused by the sun's rays mixing with car fumes could hit asthma sufferers and those with other chest complaints. Defra urged people to avoid outdoor exercise and limit car trips.

And police warned of the dangers of cooling off in rivers, lakes and canals after a 13-year-old boy drowned when he plunged into a waterfall at Haughton Green, Greater Manchester. The boy, who has not been named, disappeared under the surface of the River Tame. His body was found later.

Police said: "Many people enjoy cooling off in rivers or lakes.

"However, the water is deceptively cold and even the strongest swimmer can be quickly overcome, developing cramp and getting into difficulty."

Thames Water yesterday applied for London's first drought order since 1976 - and said standpipes in the street was a "remote possibility".

Royal parks, exempt from the hosepipe ban, will be covered by the order meaning the Queen's staff cannot water them.

A bowser used on Tony Blair's plants in Downing Street will also be hit. The order bans watering by hosepipe public gardens, parks and sports grounds. Swimming pools can not be filled or windows washed with hosepipes. Thames Water chief Joseph Pelczer said: "We already have a hosepipe ban but further restrictions may be needed by August.

"We believe it is sensible to apply for the order now. We simply don't know how much rain we will get. But normal levels of rainfall would mean the restrictions are not needed."

The order will be Britain's fourth this year. Sutton and East Surrey Water, Southern Water and Mid Kent Water already have them.